White House spokesman Joe Lockhart said US President Bill Clinton, who discussed the matter with Putin during a recent Moscow visit, expected to rehash talks on the national missile defense (NMD) system with the Russian leader this week at a gathering of leaders of industrialized nations in Japan.

"President Putin has made his views well-known on this issue," Lockhart told reporters here on the sidelines of the Camp David Middle East peace summit. "He's discussed it with the president while we were in Russia.

"I expect we'll have a further discussion in the context of the G7, G8 meetings," Lockhart said. "I think for our part, the president is still awaiting a recommendation from the secretary of defense."

He stressed that Clinton still planned to make a decision on NMD deployment based on four criteria: cost, feasibility, the threat and its effect on international security.

Earlier Tuesday, Putin, who is visiting China, told reporters in Beijing that any violation of the 1972 Anti-Ballistic Missile treaty, which would have to be amended to allow for NMD, would "destroy the world strategic balance, which would provoke a response."

"We will try to do something to maintain this balance," Putin said.

Russia and China have said the US system, which Washington says is necessary to guard against rogue states who could pose a growing nuclear threat, would undermine their nuclear deterrents and spark a new arms race.

But State Department spokesman Richard Boucher reiterated the US stance that NMD is directed neither against Russia or China, and sought to counter speculation that the Putin comments unnerved Washington.

"We don't really have any fundamental problem or any problem with close relations between Russia and China," he said.

"These are two big countries that have borders and some common interests as well as an interest in the broader world and we talk to these countries and they should talk to each other as well," he added.

President Bill Clinton is set later this year to decide whether to approve the first phase of deploying the estimated 60 billion dollar shield, which backers say is needed to thwart attacks by nations like Iran, Iraq, and North Korea.

Democratic Representative Peter DeFazio derided the system as a high-priced "comic book fantasy," warning that missile-launching nations had an arsenal of cheap countermeasures that could foil NMD. "It's time for the fantasy to stop."

"Cost estimates are beginning to float higher than the mylar balloons which the system can't distinguish from dummy warheads," said Gordon Clark, executive director of the anti-nuclear Peace Action organization.

"This cannot become a substitute for diplomacy," cautioned Democratic Representative George Miller, who urged US policymakers to step up diplomatic solutions to proliferation instead of building NMD.

The group said they would be taking the red, grey and black mock missile to the two national nominating conventions, which will formally pick the Republican and Democratic contenders to succeed Clinton.